AKR1C3, is an enzyme which belongs to the aldo/keto reductase family. It is expressed in many tissues including adrenal gland, brain, kidney, liver, lung, mammary gland, placenta, small intestine, colon, spleen, prostate and testis. AKR1C3 catalyzes the conversion of aldehydes and ketones to alcohols. It catalyzes the reduction of prostaglandin (PG) D2, PGH2 and phenanthrenequinone (PQ) and the oxidation of 9-alpha,11-beta-PGF2 to PGD2,which functions as a bi-directional 3-alpha-, 17-beta- and 20-alpha HSD. It can interconvert active androgens, estrogens and progestins with their cognate inactive metabolites.